Steam-piston packing



. 2 Sheets-Sheet 2. W. W. St JOHN; Steam-Piston Packing.

.N0.-22s,511. 'Patentedlune 8,1880.

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PATENT WILLIAM WV. ST. JOHN, OF SEDALIA, MISSOURI.

STEAM-PISTON PACKING.

SPECIFICATION formingpart of Letters Patent No. 228,571, dated June 8,1880,

Application iiled December 18, 1879.

To all whom it may concern:

Be it known that I, WILLIAM IV. ST. JOHN,

of Sedalia, in the county of Pettis and State of Missouri, have inventedcertain new and useful Improvements in Steam-Piston Packing, of whichthe following is a specification.

The object of my invention is to so pack a piston as to cause expansionoi' the sa'me by the pressure of the steam, water, air, or gas whichdrives it through a cylinder, in order that it lnay prevent leakage ofthe impelling medium between its periphery and the surface of thecylinder, and at the same to prevent leakage between thepiston and itspacking; also, to prevent undue expansion of the piston, and consequentexcessive friction between it and the cylinder 5 also, to packstuffing-boxes in a similar manner and for a similar purpose.

In accomplishing these objects my invention consists, mainly, in a rigidpacking ring or seat having in its periphery a circumferential groove,outward from the center oi' which projects an annular rib or shoulderapproximately rectangular in cross-section, and an expansible annularmetallic packing filling said groove,and having a groove 1n its innerperiphery corresponding to and embracing the annular rib or shoulder ofthe rigid ring or seat. NVhen steam or other liquid or tiuid impellingmedium presses upon one side of the piston in a cylinder it enters thenearest joint between the eXpansible packing and its seat, and, passingunder said packing, causes it to expand and press snugly against thesurface ot the cylinder 5 but while expanding the packing the steam orother medium forces it laterally, so that the wall of its groove iscaused to impinge upon the side of the annular rib or shoulder of thepacking ring or seat and form a close joint, which prevents the furtherpassage or leakage of the said impelling inedium.

It also consists in certain details of construction, which will behereinafter more particularly described.

In the accompanying drawings, Figure l is a perspective view of a pistonhaving my improved packing applied thereto. Fig. 2 is a similar view ofthe rigid ring or seat detached. Fig. 3 is a similar view of theexpansible pack- `with outward-extendin g ianges c c.

ing. Fig. 4 is a diametric section of the piston and packing. Fig. 5is aperspective view ofthe two parts of the packing ring or seat separated.Fig. 6 is a view of one of the parts of the seat or ring Witlrtheexpansible packing sprung upon it. Fig. 7 is a perspective view of twoparts of the seat or ring as cast with recesses for securing theirsoft-metal bearings, and Fig. 8 is a view ot' these parts in the moldfor forming the hearings.

The letter A indicates the piston-head. B is the packing-ring, securedin position tlush with the periphery of the same by being 'graspedbetween the edges of the two disks a a', which are connected by bolts.This packing ring or seat, for convenience in locating the packing, ashereinafter explained, I form ot' two annular parts, I) b, the adjacentedges of which are severally rabbeted and provided The rabbets of thesetwo parts form the central peripheral groove of the complete ring orpacking-seat when the said parts are placed together, as shown, and theflanges ccforln the annular rib or shoulder (J, projecting outward fromthe center of the bottom of this groove, said rib or shoulder being onlyabout onethird or one-half as high as the walls of the groove, or evenhaving a less height, as circumstances may require. From a portion ofthis rib projects outwardly an arc-shaped lug, d, having its perimeterin the same curved plane and coincident with the periphery of the ringor seat B. This lug is secured to one ofthe parts b, and the manner inwhich it is formed and located will be presently referred to.

The letter E designates the annular expansible metallic packing, theexpansion of which is permitted by a transverse division or cut, e,through its body. VIn opposite directions from the cut e are formed openslots j', which together form an opening of proper size to it snuglyaround the lug d. This packing is of cast metal, and finished up byturning in a lathe, preferably being turned off tapering slightly towardthe cut e from a point diametrically opposite said cut, this taperallowing of any expansion ot' said packing.

'In placing the parts of' my packing together the two parts bb of theseat are separated, and

IOO

the elastic packing E is then sprung around its rabbeted portion, theslotsf embracing the lug d and the ange of this rabbeted portionentering the internal groove of the packing. rlhe other portion of thering or seat is then forced into the packing, bringing the lianges b btogether in the groove of said packing. A pin, g, is then passed throughcoincident holes in the parts Z b, to assist in preventing turning ofsaid parts upon each other. When the packing is thus completed andsecured to the piston, referring to Fig. 4, it' the pressure o:l steamis in the direction of the arrow l upon said portion it will force itsway between the seat B and packing E in the direction ot' the curvedarrow, and, passing under the packing at the right-hand side of the ribC, force said packing outward a-gainst the surface of the cylinder, andat the same time the steam forces the packing laterally, so that theright-hand wall of its groove impinges forcibly against the side of therib G, forming a very close lioint, which prevents leakage of the steambetween the packing and the ring or scat. Pressure ot' steam in theopposite direction upon the piston produces, of course, a similareffect.

Thilo the lateral pressure of the packing against the rib ot' the ringprevents leakage, it also limits the quantity ot' steam passing underthe packing', and consequently limits the outward pressure of thepacking, so that there will not be excessive friction between thecylinder and said packing.

I have found it necessary, when my packing is to be used in cylinderswhich are somewhat worn, to provide the packing at that part which isits lower bearing in the cylinder with soit-metal bearings, which maymore readily iit themselves to the worn surface of the cylinder thanwould the packing of hard material. In order to forni such bearings Iform arc-shaped recesses Z l in the outer periphery oi' each ot' theparts b b, and from the bottoms ot' these recesses passages mare boredthrough inwardly. In the edge ot' each part is also formed a recess, a,and when the two parts are placed together these recesses form a passagethrough the rib C.

Now, to form the soft-metal bearings O and the arc-shaped lug` d, whichis also soft metal, I place the two parts of the packing ring or seattogether, with the packing between them, so that the slots f of saidpacking coincide with the recesses n, and slip all into a band or mold,I), which surrounds them snugly, secure them against turning byinserting the pin g, and then pour molten soft metal or compositionsuitable for bearings into the holes m and recesses u. The soft metaltills up the recesses Z and passages thereto, and also the slots f andrecesses n, to form the bearings and lug, as shown in Figs. 1,2, 5, and6. By this mode of t'ormin g the bearings and lug they are rendered veryeasily replaceable when worn out or damaged, and the packin gis readilyadapted to worn cylinders.

Vhile I have described my packing as applied to piston-heads, theprinciple of its construction enables it to be used with similar resultsas a packing for a stuffing-box, in which it will iit around apiston-rod. To adapt the packing for use in a stutting-box the parts arereversed in position-that is, the rigid seat has its groove formed inits inner periphery, and from the bottom of the groove the ribcorresponding in function to the rib G projects inwardly. The packinghas its groove formed in its outer periphery, and said packing titsinside the rigid ring or seat. The packing and its seat in this case areboth formed in segmental sections to enable them to be {itted together.

Having now described my invention, I claim- A piston-packing composed ofa rigid packing ring or seat having in its periphery a circumferentialgroove, from the center ot' the bottom of which projects an annular ribor shoulder, rectangular, or nearly so, in crossv section,.and anexpansible annular metallic packing filling said groove and having agroove in its periphery corresponi'liug to and embracing the annular ribor shoulder of the said rigid ring or seat, substantially as de scribed.

In testimony that I claim the toregoing I have hereunto set my hand inthe presence of the subscribing witnesses.

WM. XV. ST. JOHN.

Witnesses:

JAMES L. Noanis, ALBERT H. NoRRrs.

